The present invention relates to a kick-back detector in a chain saw provided with a chain brake which is released to avoid accidents when a kick-back occurs. The release of the chain brake stops any further movement of the cutting chain.
It is known in the art how to arrange a chain brake and a connected release mechanism so that the cutting chain is brought to a standstill during the early phase of a kick-back. Through the Swedish patent specification SE-A-8502688-8 (corresponding to U.S. Pat No. 4,757,881, granted July 19, 1988) it is known how to arrange a chain brake which is releasable by means of an electrically controlled release mechanism in which a charging circuit of a capacitor and a first switch is in series connected to the ignition generator of the saw, and a discharging circuit of the capacitor and a second switch are connected to an electromagnet holding a locking device of the release mechanism. In order to utilize such a control circuit to the brake in the best possible way it is required that a kick-back detector sense the kick-back movement with the least possible inertia and immediately send impulses to the control circuit thereby releasing the brake mechanism and stopping the cutting chain.